The references cited in the present application are not admitted to be prior art to the claimed invention.
About 3% of the world's population are infected with the Hepatitis C virus (HCV). (Wasley a al., Semin. Liver Dis. 20, 1-16, 2000.) Exposure to HCV results in an overt acute disease in a small percentage of cases, while in most instances the virus establishes a chronic infection causing liver inflammation and slowly progresses into liver failure and cirrhosis. (Iwarson, FEMS Microbiol. Rev. 14, 201-204, 1994.) In addition, epidemiological surveys indicate an important role of HCV in the pathogenesis of hepatocellular carcinoma. (Kew, FEMS Microbial. Rev. 14, 211-220, 1994, Alter, Blood 85, 1681-1695, 1995.)
Prior to the implementation of routine blood screening for HCV in 1992, most infections were contracted by inadvertent exposure to contaminated blood, blood products or transplanted organs. In those areas where blood screening of HCV is carried out, HCV is primarily contracted through direct percutaneous exposure to infected blood, i.e., intravenous drug use. Less frequent methods of transmission include perinatal exposure, hemodialysis, and sexual contact with an HCV infected person. (Alter et al., N. Engl. J. Med. 341(8), 556-562, 1999, Alter, J. Hepatol. 31 Suppl. 88-91, 1999. Semin. Liver. Dis. 201, 1-16, 2000.)
The HCV genome consists of a single strand RNA about 9.5 kb encoding a precursor polyprotein of about 3000 amino acids. (Choo a al., Science 244, 362-364, 1989, Choo et al., Science 244, 359-362, 1989, Takamizawa et al., J. Virol. 65, 1105-1113, 1991.) The HCV polyprotein contains the viral proteins in the order: C-E1-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS5B.
Individual viral proteins are produced by proteolysis of the HCV polyprotein. Host cell proteases release the putative structural proteins C, E1, E2, and p7, and create the N-terminus of NS2 at amino acid 810. (Mizushima et al., J. Virol. 68, 2731-2734, 1994, Hijikata et al., P.N.A.S. USA 90, 10773-10777, 1993.)
The non-structural proteins NS3, NS4A, NS4B, NS5A and NS5B presumably form the virus replication machinery and are released from the polyprotein. A zinc-dependent protease associated with NS2 and the N-terminus of NS3 is responsible for cleavage between NS2 and NS3. (Grakoui et al., J. Virol. 67, 1385-1395, 1993, Hijikata et al., P.N.A.S. USA 90, 10773-10777, 1993.) A distinct serine protease located in the N-terminal domain of NS3 is responsible for proteolytic cleavages at the NS3/NS4A, NS4A/NS4B, NS4B/NS5A and NS5A/NS5B junctions. (Bartenschlager et al., J. Virol. 67, 3835-3844, 1993, Grakoui et al., Proc. Natl. Acad. Sci. USA 90, 10583-10587, 1993, Tomei et al., J. Virol. 67, 4017-4026, 1993.) NS4A provides a cofactor for NS3 activity. (Failla et al., J. Virol. 68, 3753-3760, 1994, De Francesco et al., U.S. Pat. No. 5,739,002.)
NS5A is a highly phosphorylated protein conferring interferon resistance. (De Francesco et al., Semin. Liver Dis., 20(1), 69-83, 2000, Pawlotsky, Viral Hepat. Suppl. 1, 47-48, 1999.)
NS5B provides an RNA-dependent RNA polymerase. (De Francesco et al., International Publication Number WO 96/37619, Behrens et al., EMBO 15, 12-22, 1996, Lohmann et al., Virology 249, 108-118, 1998.)